To leave a chat room of which you’re not an owner, click on i in the top right of the room to navigate to Chat Details (Figure 1):
Figure 1 Chat Details
Click on Options, then Members Permissions (Figure 2):
Figure 2 Member Permissions
Click on Leave Room (Figure 3):
Figure 3 Leave Room
To leave a chat room of which you’re an owner, you will first need to remove yourself as an owner.
Click on i in the top right of the room to navigate to Chat Details as above. Click on Members, then View members list and hover over your name to reveal a … menu. Click the menu followed by Remove as owner (Figure 4):
Figure 4 Remove As Owner
Once you are removed as an owner, leave the chat room via the Member Permissions menu as detailed above (Figure 3).